Hydroponics is a well known technique for cultivating plants. An advantage of hydroponics over conventional soil-based techniques is that the growing environment can be greatly controlled, in particular the nutrient level provided to the root environment. A further advantage is that water provided to the plants can be readily retained in the system providing significant water savings. More recently, a technique termed Aeroponics has been developed in which the plant roots, instead of being suspended in a nutrient solution, are suspended in a fine mist of a nutrient solution. Aeroponics has advantage over hydroponics because a greater range of plants can be cultivated aeroponically
Many devices have been developed for cultivating plants using hydroponic and aeroponic techniques. These devices typically comprise a contained environment in which cuttings are suspended from a rack so that the roots are subjected to the nutrient solution or mist environment. A pump may be providing in the growing unit for circulating the nutrient solution, e.g. using an ebb and flow technique.